Please consider recommends fonts-noto-color-emoji

As was discussed earlier in the 18.04 release cycle, Qt doesn't yet have full support for color emoji. Therefore, Kubuntu includes fonts-symbola by default for black and white emoji support.

I suggest you also install fonts-noto-color-emoji by default.

In my testing, if both fonts-symbola and fonts-noto-color-emoji are installed, the Symbola emoji will be used in Qt apps and the Noto color emoji will be used in most GTK+ apps (LibreOffice, web browsers and apps based on webbrowser like Atom or Thunderbird are different).

It is reasonable to expect that a decent number of Kubuntu users will install some GTK+ apps.

I mean one other possible is for libgtk-3-0 itself to recommend fonts-noto-color-emoji but since Kubuntu includes that library, that ends up with the same result…

Optionally, if Kubuntu accepts the benefit of having color emoji support installed by default for the benefit of users of GTK+ apps, we could add fonts-noto-color-emoji to desktop-common like I originally proposed in LP: #1746310.

One more point, the text fields in GTK+ apps include an "Insert Emoji" right-click option. (There are also keyboard shortcuts: Ctrl+. or Ctrl+; to open that Insert Emoji popup and Ctrl+Shift+e to start a special quick emoji feature. Try Ctrl+shift+e then enter :-) then space for instance.) That makes emoji far more prominent in GTK+ apps than it is in Qt.